Electrochemical CO2 capture thermodynamics

Electrochemical carbon dioxide capture to close the carbon cycle

“…Alternatively, in order to decrease the required electrical energy, these steps could be integrated in a two or three-stage process [40,41] by e.g., enabling CO 2 capture or release to be performed simultaneously with electrochemical reduction or oxidation of the carrier.…”

“…Although redox-active systems have yet to achieve industrial utility, they have the potential of producing a pure CO 2 stream even from dilute gas mixtures, such as air [141]. Among different classes of redox-active compounds that have been explored, such as bipyridines [142,143], disulfides [49] and copper/amine systems [29,30], the quinone species [141,[144][145][146] are of particular interest [40], owing their strong binding affinity for CO 2 in their reduced form compared to that of their neutral state [39,147]. Quinones are organic compounds derived from aromatics, through conversion of an even number of -CH= groups into -C(=O)-groups [148].…”

“…Direct capture from air [35], ocean [8,36] and flue gas [37][38][39] have been reported. Such capture units can be retrofitted as plug-and-play processes, allow small footprints and are geometrically flexible [39,40].…”

“…They do not require external sources of heat or high pressures/ vacuum for operation, nor degradation of sorbent material is expected [40]. Although heat integration can be beneficial for power plants in reducing the need for energy, other industries (e.g., food and water sector) cannot integrate high heat, rising the need for technologies that can perform under low heat conditions from centralized emitters as well [14].…”

The refinery of today, tomorrow, and the future: A separations perspective

“…It is likely that temperature swing adsorption (TSA) processes provide among the highest if not the highest thermodynamic (2nd law) efficiencies of any separation modality focusing on capturing highly diluted target molecules (Figure 6). 31 Electrochemical separation methods potentially have even higher efficiencies when the target molecule is in a liquid solution; 32 however, issues associated with solubilization (and potential degassing) of target gas molecules still exist and may limit the overall efficiencies and productivities of these systems. Fundamentally, the primary driver behind the high efficiencies of TSA systems is the spontaneity of the adsorption process—a Langmuir‐like adsorbent with a sufficiently high affinity for the target molecule will spontaneously reach the same thermodynamic state postadsorption for a dilute feed or a concentrated feed.…”